Mary still has no respect for Edmund's profession - she has never pretended otherwise, so no surprises there.

I suspect that the flippancy of her remarks about Edmund's non-appearance in London and the old woman to be converted at Thornton Lacey conceal a good deal of worry on Mary's part.

it would not be Mary's style to moan on - "Oh, oh! why hasn't he come? Perhaps he doesn't love me", etc I think her flippancy here is partly a defence against letting herself get bogged down by unhappy feelings, and partly a defensive habit of not revealing her vulnerabilities to a world that is often unkind.